Onboard Fuel Tank Heat Evacuation for CNG and Hydrogen Refueling
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Solution Overview
Problem
High pressure gas refueling systems for hydrogen and CNG vehicles face inefficiencies due to heat buildup during refueling, leading to reduced vehicle range and increased energy consumption, as conventional methods like slow fill rates or pre-cooling are time and energy intensive.
Innovation Solution
A heat evacuation system that interconnects a tank interior heat absorber with an external heat radiator, utilizing the refueling gas to absorb and radiate compression heat, eliminating the need for slow fills, precooling, and pressure overfills, thereby optimizing tank refill efficiency and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high pressure refueling is performed at high flow rates, then refueling time is reduced, but tank interior temperature increases due to compression heat
Solution Approach 1:
The patent extracts the heat removal function from the refueling process by introducing a separate cooling system. The cooling coil and circulating fluid system are distinct from the refueling infrastructure, allowing heat to be removed from the tank interior without interfering with the high-pressure refueling operation. This enables high flow rate refueling while independently managing temperature through the extracted cooling function.
Solution Approach 2:
The patent introduces a circulating fluid as an intermediary substance to transfer heat from the tank interior to the external environment. The fluid circulates through the cooling coil, absorbing compression heat from the hydrogen tank interior and dissipating it externally. This intermediary mechanism allows heat removal without directly contacting the high-pressure hydrogen, enabling simultaneous high flow rate refueling and temperature control.
2Temperature
If conventional cooling methods are used to manage compression heat, then temperature control is achieved, but energy consumption increases
Solution Approach 1:
The patent implements a self-service cooling system where the circulating fluid continuously circulates through the cooling coil, automatically absorbing and dissipating heat without requiring external control or additional energy input. The system uses the natural circulation and heat transfer properties of the fluid to manage temperature, eliminating the need for energy-intensive active cooling mechanisms while maintaining temperature control during high-pressure refueling.
3Quantity of substance
If pressure compensation through overfill is used, then full tank capacity is achieved, but additional compression energy is required
Solution Approach 1:
The patent applies preliminary cooling to the hydrogen before it enters the tank during refueling. By removing compression heat in advance through the cooling coil system, the hydrogen can be refueled to full capacity without requiring additional pressure compensation through overfill. This preliminary temperature control allows the tank to accept the full desired quantity of hydrogen at the target pressure without the energy waste associated with overfilling and subsequent pressure regulation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system decreases refueling time, increases vehicle range, and enhances refueling efficiency by effectively managing heat buildup during high-pressure refueling, allowing for a close to optimum tank refill without additional energy or time-consuming processes.
Implementation Method 1
the refuel gas itself is circulated within the on board tank to absorb the compression heat of refueling
Implementation Method 2
the heat thereby absorbed is radiated from the cooling/refueling circuit to an external environment
Implementation Method 3
the interiors of the on board tanks become heated as a result of fuel gas compression as the tank pressure increases
Data Source
AI summary
At a high pressure refuel depot that dispenses high pressure hydrogen or compressed natural gas to vehicles, the thermal energy (heat) generated by the high flow rate of the high pressure refueling gas is evacuated from the on board fuel tank[s] of vehicles eliminating the need for refueling pre treatments such as a slow fill, secondary precooling, and pressure overfill otherwise used to achieve a full vehicle tank refill. In an example, a high pressure fuel depot refilling line is operatively interconnected to an on board vehicle tank having a gas flow circuit wherein the refuel gas itself is circulated within the on board tank to absorb the compression heat of refueling and then to an external radiator before being released into the tank.